Carbon dioxide removal using a novel adsorbent derived from calcined eggshell waste for biogas upgrading

Abstract

The existence of CO2 in biogas limits its utilization in engines by lowering its energy value and density. It contributes to global warming which is a major concern globally. The elimination of CO2 content from biogas will significantly improve the quality of biogas. In this study, biogas upgrading by calcined eggshell waste was systematically investigated. The influence of adsorbent particle size, mass, calcination temperature, and flow rate on carbon dioxide removal was studied in detail. Chemical adsorption of CO2 by calcined eggshells in a packed column having 280 and 400 μm, calcined under 800 °C, 850 °C, and 900 °C, with the mass of 25, 50, and 75 g was experimentally investigated at a different flow rate as 0.03 and 0.04 m3/h. The results revealed that a particle size of 280 μm, calcined at 850 °C, flow rate of 0.03 m3/h, and mass of 75 g perform better in the upgrading of carbon dioxide in biogas with RE and sorption of 82.5 %, and g 5.0 g/100 g respectively, creating methane enriched fuel. X-ray Fluorescence shows the presence of CaO automatically facilitates the whole process of purification. The pores were mesoporous as seen in the pore distribution curve via BET analysis while Scanning Electron Microscopy was for morphology purposes. The sorbent was successfully regenerated five times with a RE of 79.8 % and SC of 4.97 g/100 g in the first cycle. The results proved that calcined eggshells are a promising sorbent in biogas upgrading.